Some semiconductor integrated circuits (ICs) may use multiple power supplies to power internal operation, which may be external to the ICs and provided by a host system. As may often be the case, a different voltage may be provided by each of the multiple power supplies. The different voltages may be used to power different areas of the ICs and/or to power different functions performed by the ICs. When the host system powers up, however, the multiple power supplies may ramp from zero volts to their specified voltages at different rates. If an IC, for example, is powered up at a time when voltages provided by one or more of the multiple power supplies are at undesirable values with respect to one another, then the IC may not power up correctly.